/*
 * ccp.c - PPP Compression Control Protocol.
 *
 * Copyright (c) 1994-2002 Paul Mackerras. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. The name(s) of the authors of this software must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission.
 *
 * 3. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by Paul Mackerras
 *     <paulus@samba.org>".
 *
 * THE AUTHORS OF THIS SOFTWARE DISCLAIM ALL WARRANTIES WITH REGARD TO
 * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS, IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
 * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
 * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include "netif/ppp/ppp_opts.h"
#if PPP_SUPPORT && CCP_SUPPORT  /* don't build if not configured for use in lwipopts.h */

#include <stdlib.h>
#include <string.h>

#include "netif/ppp/ppp_impl.h"

#include "netif/ppp/fsm.h"
#include "netif/ppp/ccp.h"

#if MPPE_SUPPORT
	#include "netif/ppp/lcp.h"	/* lcp_close(), lcp_fsm */
	#include "netif/ppp/mppe.h"	/* mppe_init() */
#endif /* MPPE_SUPPORT */

/*
 * Unfortunately there is a bug in zlib which means that using a
 * size of 8 (window size = 256) for Deflate compression will cause
 * buffer overruns and kernel crashes in the deflate module.
 * Until this is fixed we only accept sizes in the range 9 .. 15.
 * Thanks to James Carlson for pointing this out.
 */
#define DEFLATE_MIN_WORKS	9

/*
 * Command-line options.
 */
#if PPP_OPTIONS
static int setbsdcomp(char**);
static int setdeflate(char**);
static char bsd_value[8];
static char deflate_value[8];

/*
 * Option variables.
 */
#if MPPE_SUPPORT
	bool refuse_mppe_stateful = 1;		/* Allow stateful mode? */
#endif /* MPPE_SUPPORT */

static option_t ccp_option_list[] = {
	{
		"noccp", o_bool, &ccp_protent.enabled_flag,
		"Disable CCP negotiation"
	},
	{
		"-ccp", o_bool, &ccp_protent.enabled_flag,
		"Disable CCP negotiation", OPT_ALIAS
	},

	{
		"bsdcomp", o_special, (void*)setbsdcomp,
		"Request BSD-Compress packet compression",
		OPT_PRIO | OPT_A2STRVAL | OPT_STATIC, bsd_value
	},
	{
		"nobsdcomp", o_bool, &ccp_wantoptions[0].bsd_compress,
		"don't allow BSD-Compress", OPT_PRIOSUB | OPT_A2CLR,
		&ccp_allowoptions[0].bsd_compress
	},
	{
		"-bsdcomp", o_bool, &ccp_wantoptions[0].bsd_compress,
		"don't allow BSD-Compress", OPT_ALIAS | OPT_PRIOSUB | OPT_A2CLR,
		&ccp_allowoptions[0].bsd_compress
	},

	{
		"deflate", o_special, (void*)setdeflate,
		"request Deflate compression",
		OPT_PRIO | OPT_A2STRVAL | OPT_STATIC, deflate_value
	},
	{
		"nodeflate", o_bool, &ccp_wantoptions[0].deflate,
		"don't allow Deflate compression", OPT_PRIOSUB | OPT_A2CLR,
		&ccp_allowoptions[0].deflate
	},
	{
		"-deflate", o_bool, &ccp_wantoptions[0].deflate,
		"don't allow Deflate compression", OPT_ALIAS | OPT_PRIOSUB | OPT_A2CLR,
		&ccp_allowoptions[0].deflate
	},

	{
		"nodeflatedraft", o_bool, &ccp_wantoptions[0].deflate_draft,
		"don't use draft deflate #", OPT_A2COPY,
		&ccp_allowoptions[0].deflate_draft
	},

	{
		"predictor1", o_bool, &ccp_wantoptions[0].predictor_1,
		"request Predictor-1", OPT_PRIO | 1
	},
	{
		"nopredictor1", o_bool, &ccp_wantoptions[0].predictor_1,
		"don't allow Predictor-1", OPT_PRIOSUB | OPT_A2CLR,
		&ccp_allowoptions[0].predictor_1
	},
	{
		"-predictor1", o_bool, &ccp_wantoptions[0].predictor_1,
		"don't allow Predictor-1", OPT_ALIAS | OPT_PRIOSUB | OPT_A2CLR,
		&ccp_allowoptions[0].predictor_1
	},

#if MPPE_SUPPORT
	/* MPPE options are symmetrical ... we only set wantoptions here */
	{
		"require-mppe", o_bool, &ccp_wantoptions[0].mppe,
		"require MPPE encryption",
		OPT_PRIO | MPPE_OPT_40 | MPPE_OPT_128
	},
	{
		"+mppe", o_bool, &ccp_wantoptions[0].mppe,
		"require MPPE encryption",
		OPT_ALIAS | OPT_PRIO | MPPE_OPT_40 | MPPE_OPT_128
	},
	{
		"nomppe", o_bool, &ccp_wantoptions[0].mppe,
		"don't allow MPPE encryption", OPT_PRIO
	},
	{
		"-mppe", o_bool, &ccp_wantoptions[0].mppe,
		"don't allow MPPE encryption", OPT_ALIAS | OPT_PRIO
	},

	/* We use ccp_allowoptions[0].mppe as a junk var ... it is reset later */
	{
		"require-mppe-40", o_bool, &ccp_allowoptions[0].mppe,
		"require MPPE 40-bit encryption", OPT_PRIO | OPT_A2OR | MPPE_OPT_40,
		&ccp_wantoptions[0].mppe
	},
	{
		"+mppe-40", o_bool, &ccp_allowoptions[0].mppe,
		"require MPPE 40-bit encryption", OPT_PRIO | OPT_A2OR | MPPE_OPT_40,
		&ccp_wantoptions[0].mppe
	},
	{
		"nomppe-40", o_bool, &ccp_allowoptions[0].mppe,
		"don't allow MPPE 40-bit encryption",
		OPT_PRIOSUB | OPT_A2CLRB | MPPE_OPT_40, &ccp_wantoptions[0].mppe
	},
	{
		"-mppe-40", o_bool, &ccp_allowoptions[0].mppe,
		"don't allow MPPE 40-bit encryption",
		OPT_ALIAS | OPT_PRIOSUB | OPT_A2CLRB | MPPE_OPT_40,
		&ccp_wantoptions[0].mppe
	},

	{
		"require-mppe-128", o_bool, &ccp_allowoptions[0].mppe,
		"require MPPE 128-bit encryption", OPT_PRIO | OPT_A2OR | MPPE_OPT_128,
		&ccp_wantoptions[0].mppe
	},
	{
		"+mppe-128", o_bool, &ccp_allowoptions[0].mppe,
		"require MPPE 128-bit encryption",
		OPT_ALIAS | OPT_PRIO | OPT_A2OR | MPPE_OPT_128,
		&ccp_wantoptions[0].mppe
	},
	{
		"nomppe-128", o_bool, &ccp_allowoptions[0].mppe,
		"don't allow MPPE 128-bit encryption",
		OPT_PRIOSUB | OPT_A2CLRB | MPPE_OPT_128, &ccp_wantoptions[0].mppe
	},
	{
		"-mppe-128", o_bool, &ccp_allowoptions[0].mppe,
		"don't allow MPPE 128-bit encryption",
		OPT_ALIAS | OPT_PRIOSUB | OPT_A2CLRB | MPPE_OPT_128,
		&ccp_wantoptions[0].mppe
	},

	/* strange one; we always request stateless, but will we allow stateful? */
	{
		"mppe-stateful", o_bool, &refuse_mppe_stateful,
		"allow MPPE stateful mode", OPT_PRIO
	},
	{
		"nomppe-stateful", o_bool, &refuse_mppe_stateful,
		"disallow MPPE stateful mode", OPT_PRIO | 1
	},
#endif /* MPPE_SUPPORT */

	{ NULL }
};
#endif /* PPP_OPTIONS */

/*
 * Protocol entry points from main code.
 */
static void ccp_init(ppp_pcb* pcb);
static void ccp_open(ppp_pcb* pcb);
static void ccp_close(ppp_pcb* pcb, const char* reason);
static void ccp_lowerup(ppp_pcb* pcb);
static void ccp_lowerdown(ppp_pcb* pcb);
static void ccp_input(ppp_pcb* pcb, u_char* pkt, int len);
static void ccp_protrej(ppp_pcb* pcb);
#if PRINTPKT_SUPPORT
	static int ccp_printpkt(const u_char* p, int plen, void (*printer)(void*, const char*, ...), void* arg);
#endif /* PRINTPKT_SUPPORT */
#if PPP_DATAINPUT
	static void ccp_datainput(ppp_pcb* pcb, u_char* pkt, int len);
#endif /* PPP_DATAINPUT */

const struct protent ccp_protent = {
	PPP_CCP,
	ccp_init,
	ccp_input,
	ccp_protrej,
	ccp_lowerup,
	ccp_lowerdown,
	ccp_open,
	ccp_close,
#if PRINTPKT_SUPPORT
	ccp_printpkt,
#endif /* PRINTPKT_SUPPORT */
#if PPP_DATAINPUT
	ccp_datainput,
#endif /* PPP_DATAINPUT */
#if PRINTPKT_SUPPORT
	"CCP",
	"Compressed",
#endif /* PRINTPKT_SUPPORT */
#if PPP_OPTIONS
	ccp_option_list,
	NULL,
#endif /* PPP_OPTIONS */
#if DEMAND_SUPPORT
	NULL,
	NULL
#endif /* DEMAND_SUPPORT */
};

/*
 * Callbacks for fsm code.
 */
static void ccp_resetci(fsm*);
static int  ccp_cilen(fsm*);
static void ccp_addci(fsm*, u_char*, int*);
static int  ccp_ackci(fsm*, u_char*, int);
static int  ccp_nakci(fsm*, u_char*, int, int);
static int  ccp_rejci(fsm*, u_char*, int);
static int  ccp_reqci(fsm*, u_char*, int*, int);
static void ccp_up(fsm*);
static void ccp_down(fsm*);
static int  ccp_extcode(fsm*, int, int, u_char*, int);
static void ccp_rack_timeout(void*);
static const char* method_name(ccp_options*, ccp_options*);

static const fsm_callbacks ccp_callbacks = {
	ccp_resetci,
	ccp_cilen,
	ccp_addci,
	ccp_ackci,
	ccp_nakci,
	ccp_rejci,
	ccp_reqci,
	ccp_up,
	ccp_down,
	NULL,
	NULL,
	NULL,
	NULL,
	ccp_extcode,
	"CCP"
};

/*
 * Do we want / did we get any compression?
 */
static int ccp_anycompress(ccp_options* opt)
{
	return (0
#if DEFLATE_SUPPORT
	        || (opt)->deflate
#endif /* DEFLATE_SUPPORT */
#if BSDCOMPRESS_SUPPORT
	        || (opt)->bsd_compress
#endif /* BSDCOMPRESS_SUPPORT */
#if PREDICTOR_SUPPORT
	        || (opt)->predictor_1 || (opt)->predictor_2
#endif /* PREDICTOR_SUPPORT */
#if MPPE_SUPPORT
	        || (opt)->mppe
#endif /* MPPE_SUPPORT */
	       );
}

/*
 * Local state (mainly for handling reset-reqs and reset-acks).
 */
#define RACK_PENDING	1	/* waiting for reset-ack */
#define RREQ_REPEAT	2	/* send another reset-req if no reset-ack */

#define RACKTIMEOUT	1	/* second */

#if PPP_OPTIONS
/*
 * Option parsing
 */
static int
setbsdcomp(argv)
char** argv;
{
	int rbits, abits;
	char* str, *endp;

	str = *argv;
	abits = rbits = strtol(str, &endp, 0);

	if(endp != str && *endp == ',') {
		str = endp + 1;
		abits = strtol(str, &endp, 0);
	}

	if(*endp != 0 || endp == str) {
		option_error("invalid parameter '%s' for bsdcomp option", *argv);
		return 0;
	}

	if((rbits != 0 && (rbits < BSD_MIN_BITS || rbits > BSD_MAX_BITS))
	        || (abits != 0 && (abits < BSD_MIN_BITS || abits > BSD_MAX_BITS))) {
		option_error("bsdcomp option values must be 0 or %d .. %d",
		             BSD_MIN_BITS, BSD_MAX_BITS);
		return 0;
	}

	if(rbits > 0) {
		ccp_wantoptions[0].bsd_compress = 1;
		ccp_wantoptions[0].bsd_bits = rbits;
	} else
		ccp_wantoptions[0].bsd_compress = 0;

	if(abits > 0) {
		ccp_allowoptions[0].bsd_compress = 1;
		ccp_allowoptions[0].bsd_bits = abits;
	} else
		ccp_allowoptions[0].bsd_compress = 0;

	ppp_slprintf(bsd_value, sizeof(bsd_value),
	             rbits == abits ? "%d" : "%d,%d", rbits, abits);

	return 1;
}

static int
setdeflate(argv)
char** argv;
{
	int rbits, abits;
	char* str, *endp;

	str = *argv;
	abits = rbits = strtol(str, &endp, 0);

	if(endp != str && *endp == ',') {
		str = endp + 1;
		abits = strtol(str, &endp, 0);
	}

	if(*endp != 0 || endp == str) {
		option_error("invalid parameter '%s' for deflate option", *argv);
		return 0;
	}

	if((rbits != 0 && (rbits < DEFLATE_MIN_SIZE || rbits > DEFLATE_MAX_SIZE))
	        || (abits != 0 && (abits < DEFLATE_MIN_SIZE
	                           || abits > DEFLATE_MAX_SIZE))) {
		option_error("deflate option values must be 0 or %d .. %d",
		             DEFLATE_MIN_SIZE, DEFLATE_MAX_SIZE);
		return 0;
	}

	if(rbits == DEFLATE_MIN_SIZE || abits == DEFLATE_MIN_SIZE) {
		if(rbits == DEFLATE_MIN_SIZE)
			rbits = DEFLATE_MIN_WORKS;

		if(abits == DEFLATE_MIN_SIZE)
			abits = DEFLATE_MIN_WORKS;

		warn("deflate option value of %d changed to %d to avoid zlib bug",
		     DEFLATE_MIN_SIZE, DEFLATE_MIN_WORKS);
	}

	if(rbits > 0) {
		ccp_wantoptions[0].deflate = 1;
		ccp_wantoptions[0].deflate_size = rbits;
	} else
		ccp_wantoptions[0].deflate = 0;

	if(abits > 0) {
		ccp_allowoptions[0].deflate = 1;
		ccp_allowoptions[0].deflate_size = abits;
	} else
		ccp_allowoptions[0].deflate = 0;

	ppp_slprintf(deflate_value, sizeof(deflate_value),
	             rbits == abits ? "%d" : "%d,%d", rbits, abits);

	return 1;
}
#endif /* PPP_OPTIONS */

/*
 * ccp_init - initialize CCP.
 */
static void ccp_init(ppp_pcb* pcb)
{
	fsm* f = &pcb->ccp_fsm;

	f->pcb = pcb;
	f->protocol = PPP_CCP;
	f->callbacks = &ccp_callbacks;
	fsm_init(f);

#if 0 /* Not necessary, everything is cleared in ppp_new() */
	memset(wo, 0, sizeof(*wo));
	memset(go, 0, sizeof(*go));
	memset(ao, 0, sizeof(*ao));
	memset(ho, 0, sizeof(*ho));
#endif /* 0 */

#if DEFLATE_SUPPORT
	wo->deflate = 1;
	wo->deflate_size = DEFLATE_MAX_SIZE;
	wo->deflate_correct = 1;
	wo->deflate_draft = 1;
	ao->deflate = 1;
	ao->deflate_size = DEFLATE_MAX_SIZE;
	ao->deflate_correct = 1;
	ao->deflate_draft = 1;
#endif /* DEFLATE_SUPPORT */

#if BSDCOMPRESS_SUPPORT
	wo->bsd_compress = 1;
	wo->bsd_bits = BSD_MAX_BITS;
	ao->bsd_compress = 1;
	ao->bsd_bits = BSD_MAX_BITS;
#endif /* BSDCOMPRESS_SUPPORT */

#if PREDICTOR_SUPPORT
	ao->predictor_1 = 1;
#endif /* PREDICTOR_SUPPORT */
}

/*
 * ccp_open - CCP is allowed to come up.
 */
static void ccp_open(ppp_pcb* pcb)
{
	fsm* f = &pcb->ccp_fsm;
	ccp_options* go = &pcb->ccp_gotoptions;

	if(f->state != PPP_FSM_OPENED)
		ccp_set(pcb, 1, 0, 0, 0);

	/*
	 * Find out which compressors the kernel supports before
	 * deciding whether to open in silent mode.
	 */
	ccp_resetci(f);

	if(!ccp_anycompress(go))
		f->flags |= OPT_SILENT;

	fsm_open(f);
}

/*
 * ccp_close - Terminate CCP.
 */
static void ccp_close(ppp_pcb* pcb, const char* reason)
{
	fsm* f = &pcb->ccp_fsm;
	ccp_set(pcb, 0, 0, 0, 0);
	fsm_close(f, reason);
}

/*
 * ccp_lowerup - we may now transmit CCP packets.
 */
static void ccp_lowerup(ppp_pcb* pcb)
{
	fsm* f = &pcb->ccp_fsm;
	fsm_lowerup(f);
}

/*
 * ccp_lowerdown - we may not transmit CCP packets.
 */
static void ccp_lowerdown(ppp_pcb* pcb)
{
	fsm* f = &pcb->ccp_fsm;
	fsm_lowerdown(f);
}

/*
 * ccp_input - process a received CCP packet.
 */
static void ccp_input(ppp_pcb* pcb, u_char* p, int len)
{
	fsm* f = &pcb->ccp_fsm;
	ccp_options* go = &pcb->ccp_gotoptions;
	int oldstate;

	/*
	 * Check for a terminate-request so we can print a message.
	 */
	oldstate = f->state;
	fsm_input(f, p, len);

	if(oldstate == PPP_FSM_OPENED && p[0] == TERMREQ && f->state != PPP_FSM_OPENED) {
		ppp_notice("Compression disabled by peer.");
#if MPPE_SUPPORT

		if(go->mppe) {
			ppp_error("MPPE disabled, closing LCP");
			lcp_close(pcb, "MPPE disabled by peer");
		}

#endif /* MPPE_SUPPORT */
	}

	/*
	 * If we get a terminate-ack and we're not asking for compression,
	 * close CCP.
	 */
	if(oldstate == PPP_FSM_REQSENT && p[0] == TERMACK
	        && !ccp_anycompress(go))
		ccp_close(pcb, "No compression negotiated");
}

/*
 * Handle a CCP-specific code.
 */
static int ccp_extcode(fsm* f, int code, int id, u_char* p, int len)
{
	ppp_pcb* pcb = f->pcb;
	LWIP_UNUSED_ARG(p);
	LWIP_UNUSED_ARG(len);

	switch(code) {
		case CCP_RESETREQ:
			if(f->state != PPP_FSM_OPENED)
				break;

			ccp_reset_comp(pcb);
			/* send a reset-ack, which the transmitter will see and
			   reset its compression state. */
			fsm_sdata(f, CCP_RESETACK, id, NULL, 0);
			break;

		case CCP_RESETACK:
			if((pcb->ccp_localstate & RACK_PENDING) && id == f->reqid) {
				pcb->ccp_localstate &= ~(RACK_PENDING | RREQ_REPEAT);
				UNTIMEOUT(ccp_rack_timeout, f);
				ccp_reset_decomp(pcb);
			}

			break;

		default:
			return 0;
	}

	return 1;
}

/*
 * ccp_protrej - peer doesn't talk CCP.
 */
static void ccp_protrej(ppp_pcb* pcb)
{
	fsm* f = &pcb->ccp_fsm;
#if MPPE_SUPPORT
	ccp_options* go = &pcb->ccp_gotoptions;
#endif /* MPPE_SUPPORT */

	ccp_set(pcb, 0, 0, 0, 0);
	fsm_lowerdown(f);

#if MPPE_SUPPORT

	if(go->mppe) {
		ppp_error("MPPE required but peer negotiation failed");
		lcp_close(pcb, "MPPE required but peer negotiation failed");
	}

#endif /* MPPE_SUPPORT */

}

/*
 * ccp_resetci - initialize at start of negotiation.
 */
static void ccp_resetci(fsm* f)
{
	ppp_pcb* pcb = f->pcb;
	ccp_options* go = &pcb->ccp_gotoptions;
	ccp_options* wo = &pcb->ccp_wantoptions;
#if MPPE_SUPPORT
	ccp_options* ao = &pcb->ccp_allowoptions;
#endif /* MPPE_SUPPORT */
#if DEFLATE_SUPPORT || BSDCOMPRESS_SUPPORT || PREDICTOR_SUPPORT
	u_char opt_buf[CCP_MAX_OPTION_LENGTH];
#endif /* DEFLATE_SUPPORT || BSDCOMPRESS_SUPPORT || PREDICTOR_SUPPORT */
#if DEFLATE_SUPPORT || BSDCOMPRESS_SUPPORT
	int res;
#endif /* DEFLATE_SUPPORT || BSDCOMPRESS_SUPPORT */

#if MPPE_SUPPORT

	if(pcb->settings.require_mppe) {
		wo->mppe = ao->mppe =
		               (pcb->settings.refuse_mppe_40 ? 0 : MPPE_OPT_40)
		               | (pcb->settings.refuse_mppe_128 ? 0 : MPPE_OPT_128);
	}

#endif /* MPPE_SUPPORT */

	*go = *wo;
	pcb->ccp_all_rejected = 0;

#if MPPE_SUPPORT

	if(go->mppe) {
		int auth_mschap_bits = pcb->auth_done;
		int numbits;

		/*
		 * Start with a basic sanity check: mschap[v2] auth must be in
		 * exactly one direction.  RFC 3079 says that the keys are
		 * 'derived from the credentials of the peer that initiated the call',
		 * however the PPP protocol doesn't have such a concept, and pppd
		 * cannot get this info externally.  Instead we do the best we can.
		 * NB: If MPPE is required, all other compression opts are invalid.
		 *     So, we return right away if we can't do it.
		 */

		/* Leave only the mschap auth bits set */
		auth_mschap_bits &= (CHAP_MS_WITHPEER  | CHAP_MS_PEER |
		                     CHAP_MS2_WITHPEER | CHAP_MS2_PEER);
		/* Count the mschap auths */
		auth_mschap_bits >>= CHAP_MS_SHIFT;
		numbits = 0;

		do {
			numbits += auth_mschap_bits & 1;
			auth_mschap_bits >>= 1;
		} while(auth_mschap_bits);

		if(numbits > 1) {
			ppp_error("MPPE required, but auth done in both directions.");
			lcp_close(pcb, "MPPE required but not available");
			return;
		}

		if(!numbits) {
			ppp_error("MPPE required, but MS-CHAP[v2] auth not performed.");
			lcp_close(pcb, "MPPE required but not available");
			return;
		}

		/* A plugin (eg radius) may not have obtained key material. */
		if(!pcb->mppe_keys_set) {
			ppp_error("MPPE required, but keys are not available.  "
			          "Possible plugin problem?");
			lcp_close(pcb, "MPPE required but not available");
			return;
		}

		/* LM auth not supported for MPPE */
		if(pcb->auth_done & (CHAP_MS_WITHPEER | CHAP_MS_PEER)) {
			/* This might be noise */
			if(go->mppe & MPPE_OPT_40) {
				ppp_notice("Disabling 40-bit MPPE; MS-CHAP LM not supported");
				go->mppe &= ~MPPE_OPT_40;
				wo->mppe &= ~MPPE_OPT_40;
			}
		}

		/* Last check: can we actually negotiate something? */
		if(!(go->mppe & (MPPE_OPT_40 | MPPE_OPT_128))) {
			/* Could be misconfig, could be 40-bit disabled above. */
			ppp_error("MPPE required, but both 40-bit and 128-bit disabled.");
			lcp_close(pcb, "MPPE required but not available");
			return;
		}

		/* sync options */
		ao->mppe = go->mppe;
		/* MPPE is not compatible with other compression types */
#if BSDCOMPRESS_SUPPORT
		ao->bsd_compress = go->bsd_compress = 0;
#endif /* BSDCOMPRESS_SUPPORT */
#if PREDICTOR_SUPPORT
		ao->predictor_1  = go->predictor_1  = 0;
		ao->predictor_2  = go->predictor_2  = 0;
#endif /* PREDICTOR_SUPPORT */
#if DEFLATE_SUPPORT
		ao->deflate      = go->deflate      = 0;
#endif /* DEFLATE_SUPPORT */
	}

#endif /* MPPE_SUPPORT */

	/*
	 * Check whether the kernel knows about the various
	 * compression methods we might request.
	 */
#if BSDCOMPRESS_SUPPORT

	/* FIXME: we don't need to test if BSD compress is available
	 * if BSDCOMPRESS_SUPPORT is set, it is.
	 */
	if(go->bsd_compress) {
		opt_buf[0] = CI_BSD_COMPRESS;
		opt_buf[1] = CILEN_BSD_COMPRESS;

		for(;;) {
			if(go->bsd_bits < BSD_MIN_BITS) {
				go->bsd_compress = 0;
				break;
			}

			opt_buf[2] = BSD_MAKE_OPT(BSD_CURRENT_VERSION, go->bsd_bits);
			res = ccp_test(pcb, opt_buf, CILEN_BSD_COMPRESS, 0);

			if(res > 0) {
				break;
			} else if(res < 0) {
				go->bsd_compress = 0;
				break;
			}

			go->bsd_bits--;
		}
	}

#endif /* BSDCOMPRESS_SUPPORT */
#if DEFLATE_SUPPORT

	/* FIXME: we don't need to test if deflate is available
	 * if DEFLATE_SUPPORT is set, it is.
	 */
	if(go->deflate) {
		if(go->deflate_correct) {
			opt_buf[0] = CI_DEFLATE;
			opt_buf[1] = CILEN_DEFLATE;
			opt_buf[3] = DEFLATE_CHK_SEQUENCE;

			for(;;) {
				if(go->deflate_size < DEFLATE_MIN_WORKS) {
					go->deflate_correct = 0;
					break;
				}

				opt_buf[2] = DEFLATE_MAKE_OPT(go->deflate_size);
				res = ccp_test(pcb, opt_buf, CILEN_DEFLATE, 0);

				if(res > 0) {
					break;
				} else if(res < 0) {
					go->deflate_correct = 0;
					break;
				}

				go->deflate_size--;
			}
		}

		if(go->deflate_draft) {
			opt_buf[0] = CI_DEFLATE_DRAFT;
			opt_buf[1] = CILEN_DEFLATE;
			opt_buf[3] = DEFLATE_CHK_SEQUENCE;

			for(;;) {
				if(go->deflate_size < DEFLATE_MIN_WORKS) {
					go->deflate_draft = 0;
					break;
				}

				opt_buf[2] = DEFLATE_MAKE_OPT(go->deflate_size);
				res = ccp_test(pcb, opt_buf, CILEN_DEFLATE, 0);

				if(res > 0) {
					break;
				} else if(res < 0) {
					go->deflate_draft = 0;
					break;
				}

				go->deflate_size--;
			}
		}

		if(!go->deflate_correct && !go->deflate_draft)
			go->deflate = 0;
	}

#endif /* DEFLATE_SUPPORT */
#if PREDICTOR_SUPPORT

	/* FIXME: we don't need to test if predictor is available,
	 * if PREDICTOR_SUPPORT is set, it is.
	 */
	if(go->predictor_1) {
		opt_buf[0] = CI_PREDICTOR_1;
		opt_buf[1] = CILEN_PREDICTOR_1;

		if(ccp_test(pcb, opt_buf, CILEN_PREDICTOR_1, 0) <= 0)
			go->predictor_1 = 0;
	}

	if(go->predictor_2) {
		opt_buf[0] = CI_PREDICTOR_2;
		opt_buf[1] = CILEN_PREDICTOR_2;

		if(ccp_test(pcb, opt_buf, CILEN_PREDICTOR_2, 0) <= 0)
			go->predictor_2 = 0;
	}

#endif /* PREDICTOR_SUPPORT */
}

/*
 * ccp_cilen - Return total length of our configuration info.
 */
static int ccp_cilen(fsm* f)
{
	ppp_pcb* pcb = f->pcb;
	ccp_options* go = &pcb->ccp_gotoptions;

	return 0
#if BSDCOMPRESS_SUPPORT
	       + (go->bsd_compress ? CILEN_BSD_COMPRESS : 0)
#endif /* BSDCOMPRESS_SUPPORT */
#if DEFLATE_SUPPORT
	       + (go->deflate && go->deflate_correct ? CILEN_DEFLATE : 0)
	       + (go->deflate && go->deflate_draft ? CILEN_DEFLATE : 0)
#endif /* DEFLATE_SUPPORT */
#if PREDICTOR_SUPPORT
	       + (go->predictor_1 ? CILEN_PREDICTOR_1 : 0)
	       + (go->predictor_2 ? CILEN_PREDICTOR_2 : 0)
#endif /* PREDICTOR_SUPPORT */
#if MPPE_SUPPORT
	       + (go->mppe ? CILEN_MPPE : 0)
#endif /* MPPE_SUPPORT */
	       ;
}

/*
 * ccp_addci - put our requests in a packet.
 */
static void ccp_addci(fsm* f, u_char* p, int* lenp)
{
	ppp_pcb* pcb = f->pcb;
	ccp_options* go = &pcb->ccp_gotoptions;
	u_char* p0 = p;

	/*
	 * Add the compression types that we can receive, in decreasing
	 * preference order.
	 */
#if MPPE_SUPPORT

	if(go->mppe) {
		p[0] = CI_MPPE;
		p[1] = CILEN_MPPE;
		MPPE_OPTS_TO_CI(go->mppe, &p[2]);
		mppe_init(pcb, &pcb->mppe_decomp, go->mppe);
		p += CILEN_MPPE;
	}

#endif /* MPPE_SUPPORT */
#if DEFLATE_SUPPORT

	if(go->deflate) {
		if(go->deflate_correct) {
			p[0] = CI_DEFLATE;
			p[1] = CILEN_DEFLATE;
			p[2] = DEFLATE_MAKE_OPT(go->deflate_size);
			p[3] = DEFLATE_CHK_SEQUENCE;
			p += CILEN_DEFLATE;
		}

		if(go->deflate_draft) {
			p[0] = CI_DEFLATE_DRAFT;
			p[1] = CILEN_DEFLATE;
			p[2] = p[2 - CILEN_DEFLATE];
			p[3] = DEFLATE_CHK_SEQUENCE;
			p += CILEN_DEFLATE;
		}
	}

#endif /* DEFLATE_SUPPORT */
#if BSDCOMPRESS_SUPPORT

	if(go->bsd_compress) {
		p[0] = CI_BSD_COMPRESS;
		p[1] = CILEN_BSD_COMPRESS;
		p[2] = BSD_MAKE_OPT(BSD_CURRENT_VERSION, go->bsd_bits);
		p += CILEN_BSD_COMPRESS;
	}

#endif /* BSDCOMPRESS_SUPPORT */
#if PREDICTOR_SUPPORT

	/* XXX Should Predictor 2 be preferable to Predictor 1? */
	if(go->predictor_1) {
		p[0] = CI_PREDICTOR_1;
		p[1] = CILEN_PREDICTOR_1;
		p += CILEN_PREDICTOR_1;
	}

	if(go->predictor_2) {
		p[0] = CI_PREDICTOR_2;
		p[1] = CILEN_PREDICTOR_2;
		p += CILEN_PREDICTOR_2;
	}

#endif /* PREDICTOR_SUPPORT */

	go->method = (p > p0) ? p0[0] : 0;

	*lenp = p - p0;
}

/*
 * ccp_ackci - process a received configure-ack, and return
 * 1 iff the packet was OK.
 */
static int ccp_ackci(fsm* f, u_char* p, int len)
{
	ppp_pcb* pcb = f->pcb;
	ccp_options* go = &pcb->ccp_gotoptions;
#if BSDCOMPRESS_SUPPORT || PREDICTOR_SUPPORT
	u_char* p0 = p;
#endif /* BSDCOMPRESS_SUPPORT || PREDICTOR_SUPPORT */

#if MPPE_SUPPORT

	if(go->mppe) {
		u_char opt_buf[CILEN_MPPE];

		opt_buf[0] = CI_MPPE;
		opt_buf[1] = CILEN_MPPE;
		MPPE_OPTS_TO_CI(go->mppe, &opt_buf[2]);

		if(len < CILEN_MPPE || memcmp(opt_buf, p, CILEN_MPPE))
			return 0;

		p += CILEN_MPPE;
		len -= CILEN_MPPE;

		/* XXX Cope with first/fast ack */
		if(len == 0)
			return 1;
	}

#endif /* MPPE_SUPPORT */
#if DEFLATE_SUPPORT

	if(go->deflate) {
		if(len < CILEN_DEFLATE
		        || p[0] != (go->deflate_correct ? CI_DEFLATE : CI_DEFLATE_DRAFT)
		        || p[1] != CILEN_DEFLATE
		        || p[2] != DEFLATE_MAKE_OPT(go->deflate_size)
		        || p[3] != DEFLATE_CHK_SEQUENCE)
			return 0;

		p += CILEN_DEFLATE;
		len -= CILEN_DEFLATE;

		/* XXX Cope with first/fast ack */
		if(len == 0)
			return 1;

		if(go->deflate_correct && go->deflate_draft) {
			if(len < CILEN_DEFLATE
			        || p[0] != CI_DEFLATE_DRAFT
			        || p[1] != CILEN_DEFLATE
			        || p[2] != DEFLATE_MAKE_OPT(go->deflate_size)
			        || p[3] != DEFLATE_CHK_SEQUENCE)
				return 0;

			p += CILEN_DEFLATE;
			len -= CILEN_DEFLATE;
		}
	}

#endif /* DEFLATE_SUPPORT */
#if BSDCOMPRESS_SUPPORT

	if(go->bsd_compress) {
		if(len < CILEN_BSD_COMPRESS
		        || p[0] != CI_BSD_COMPRESS || p[1] != CILEN_BSD_COMPRESS
		        || p[2] != BSD_MAKE_OPT(BSD_CURRENT_VERSION, go->bsd_bits))
			return 0;

		p += CILEN_BSD_COMPRESS;
		len -= CILEN_BSD_COMPRESS;

		/* XXX Cope with first/fast ack */
		if(p == p0 && len == 0)
			return 1;
	}

#endif /* BSDCOMPRESS_SUPPORT */
#if PREDICTOR_SUPPORT

	if(go->predictor_1) {
		if(len < CILEN_PREDICTOR_1
		        || p[0] != CI_PREDICTOR_1 || p[1] != CILEN_PREDICTOR_1)
			return 0;

		p += CILEN_PREDICTOR_1;
		len -= CILEN_PREDICTOR_1;

		/* XXX Cope with first/fast ack */
		if(p == p0 && len == 0)
			return 1;
	}

	if(go->predictor_2) {
		if(len < CILEN_PREDICTOR_2
		        || p[0] != CI_PREDICTOR_2 || p[1] != CILEN_PREDICTOR_2)
			return 0;

		p += CILEN_PREDICTOR_2;
		len -= CILEN_PREDICTOR_2;

		/* XXX Cope with first/fast ack */
		if(p == p0 && len == 0)
			return 1;
	}

#endif /* PREDICTOR_SUPPORT */

	if(len != 0)
		return 0;

	return 1;
}

/*
 * ccp_nakci - process received configure-nak.
 * Returns 1 iff the nak was OK.
 */
static int ccp_nakci(fsm* f, u_char* p, int len, int treat_as_reject)
{
	ppp_pcb* pcb = f->pcb;
	ccp_options* go = &pcb->ccp_gotoptions;
	ccp_options no;		/* options we've seen already */
	ccp_options try_;		/* options to ask for next time */
	LWIP_UNUSED_ARG(treat_as_reject);
#if !MPPE_SUPPORT && !DEFLATE_SUPPORT && !BSDCOMPRESS_SUPPORT
	LWIP_UNUSED_ARG(p);
	LWIP_UNUSED_ARG(len);
#endif /* !MPPE_SUPPORT && !DEFLATE_SUPPORT && !BSDCOMPRESS_SUPPORT */

	memset(&no, 0, sizeof(no));
	try_ = *go;

#if MPPE_SUPPORT

	if(go->mppe && len >= CILEN_MPPE
	        && p[0] == CI_MPPE && p[1] == CILEN_MPPE) {
		no.mppe = 1;
		/*
		 * Peer wants us to use a different strength or other setting.
		 * Fail if we aren't willing to use his suggestion.
		 */
		MPPE_CI_TO_OPTS(&p[2], try_.mppe);

		if((try_.mppe & MPPE_OPT_STATEFUL) && pcb->settings.refuse_mppe_stateful) {
			ppp_error("Refusing MPPE stateful mode offered by peer");
			try_.mppe = 0;
		} else if(((go->mppe | MPPE_OPT_STATEFUL) & try_.mppe) != try_.mppe) {
			/* Peer must have set options we didn't request (suggest) */
			try_.mppe = 0;
		}

		if(!try_.mppe) {
			ppp_error("MPPE required but peer negotiation failed");
			lcp_close(pcb, "MPPE required but peer negotiation failed");
		}
	}

#endif /* MPPE_SUPPORT */
#if DEFLATE_SUPPORT

	if(go->deflate && len >= CILEN_DEFLATE
	        && p[0] == (go->deflate_correct ? CI_DEFLATE : CI_DEFLATE_DRAFT)
	        && p[1] == CILEN_DEFLATE) {
		no.deflate = 1;

		/*
		 * Peer wants us to use a different code size or something.
		 * Stop asking for Deflate if we don't understand his suggestion.
		 */
		if(DEFLATE_METHOD(p[2]) != DEFLATE_METHOD_VAL
		        || DEFLATE_SIZE(p[2]) < DEFLATE_MIN_WORKS
		        || p[3] != DEFLATE_CHK_SEQUENCE)
			try_.deflate = 0;
		else if(DEFLATE_SIZE(p[2]) < go->deflate_size)
			try_.deflate_size = DEFLATE_SIZE(p[2]);

		p += CILEN_DEFLATE;
		len -= CILEN_DEFLATE;

		if(go->deflate_correct && go->deflate_draft
		        && len >= CILEN_DEFLATE && p[0] == CI_DEFLATE_DRAFT
		        && p[1] == CILEN_DEFLATE) {
			p += CILEN_DEFLATE;
			len -= CILEN_DEFLATE;
		}
	}

#endif /* DEFLATE_SUPPORT */
#if BSDCOMPRESS_SUPPORT

	if(go->bsd_compress && len >= CILEN_BSD_COMPRESS
	        && p[0] == CI_BSD_COMPRESS && p[1] == CILEN_BSD_COMPRESS) {
		no.bsd_compress = 1;

		/*
		 * Peer wants us to use a different number of bits
		 * or a different version.
		 */
		if(BSD_VERSION(p[2]) != BSD_CURRENT_VERSION)
			try_.bsd_compress = 0;
		else if(BSD_NBITS(p[2]) < go->bsd_bits)
			try_.bsd_bits = BSD_NBITS(p[2]);

		p += CILEN_BSD_COMPRESS;
		len -= CILEN_BSD_COMPRESS;
	}

#endif /* BSDCOMPRESS_SUPPORT */

	/*
	 * Predictor-1 and 2 have no options, so they can't be Naked.
	 *
	 * There may be remaining options but we ignore them.
	 */

	if(f->state != PPP_FSM_OPENED)
		*go = try_;

	return 1;
}

/*
 * ccp_rejci - reject some of our suggested compression methods.
 */
static int ccp_rejci(fsm* f, u_char* p, int len)
{
	ppp_pcb* pcb = f->pcb;
	ccp_options* go = &pcb->ccp_gotoptions;
	ccp_options try_;		/* options to request next time */

	try_ = *go;

	/*
	 * Cope with empty configure-rejects by ceasing to send
	 * configure-requests.
	 */
	if(len == 0 && pcb->ccp_all_rejected)
		return -1;

#if MPPE_SUPPORT

	if(go->mppe && len >= CILEN_MPPE
	        && p[0] == CI_MPPE && p[1] == CILEN_MPPE) {
		ppp_error("MPPE required but peer refused");
		lcp_close(pcb, "MPPE required but peer refused");
		p += CILEN_MPPE;
		len -= CILEN_MPPE;
	}

#endif /* MPPE_SUPPORT */
#if DEFLATE_SUPPORT

	if(go->deflate_correct && len >= CILEN_DEFLATE
	        && p[0] == CI_DEFLATE && p[1] == CILEN_DEFLATE) {
		if(p[2] != DEFLATE_MAKE_OPT(go->deflate_size)
		        || p[3] != DEFLATE_CHK_SEQUENCE)
			return 0;		/* Rej is bad */

		try_.deflate_correct = 0;
		p += CILEN_DEFLATE;
		len -= CILEN_DEFLATE;
	}

	if(go->deflate_draft && len >= CILEN_DEFLATE
	        && p[0] == CI_DEFLATE_DRAFT && p[1] == CILEN_DEFLATE) {
		if(p[2] != DEFLATE_MAKE_OPT(go->deflate_size)
		        || p[3] != DEFLATE_CHK_SEQUENCE)
			return 0;		/* Rej is bad */

		try_.deflate_draft = 0;
		p += CILEN_DEFLATE;
		len -= CILEN_DEFLATE;
	}

	if(!try_.deflate_correct && !try_.deflate_draft)
		try_.deflate = 0;

#endif /* DEFLATE_SUPPORT */
#if BSDCOMPRESS_SUPPORT

	if(go->bsd_compress && len >= CILEN_BSD_COMPRESS
	        && p[0] == CI_BSD_COMPRESS && p[1] == CILEN_BSD_COMPRESS) {
		if(p[2] != BSD_MAKE_OPT(BSD_CURRENT_VERSION, go->bsd_bits))
			return 0;

		try_.bsd_compress = 0;
		p += CILEN_BSD_COMPRESS;
		len -= CILEN_BSD_COMPRESS;
	}

#endif /* BSDCOMPRESS_SUPPORT */
#if PREDICTOR_SUPPORT

	if(go->predictor_1 && len >= CILEN_PREDICTOR_1
	        && p[0] == CI_PREDICTOR_1 && p[1] == CILEN_PREDICTOR_1) {
		try_.predictor_1 = 0;
		p += CILEN_PREDICTOR_1;
		len -= CILEN_PREDICTOR_1;
	}

	if(go->predictor_2 && len >= CILEN_PREDICTOR_2
	        && p[0] == CI_PREDICTOR_2 && p[1] == CILEN_PREDICTOR_2) {
		try_.predictor_2 = 0;
		p += CILEN_PREDICTOR_2;
		len -= CILEN_PREDICTOR_2;
	}

#endif /* PREDICTOR_SUPPORT */

	if(len != 0)
		return 0;

	if(f->state != PPP_FSM_OPENED)
		*go = try_;

	return 1;
}

/*
 * ccp_reqci - processed a received configure-request.
 * Returns CONFACK, CONFNAK or CONFREJ and the packet modified
 * appropriately.
 */
static int ccp_reqci(fsm* f, u_char* p, int* lenp, int dont_nak)
{
	ppp_pcb* pcb = f->pcb;
	ccp_options* ho = &pcb->ccp_hisoptions;
	ccp_options* ao = &pcb->ccp_allowoptions;
	int ret, newret;
#if DEFLATE_SUPPORT || BSDCOMPRESS_SUPPORT
	int res;
	int nb;
#endif /* DEFLATE_SUPPORT || BSDCOMPRESS_SUPPORT */
	u_char* p0, *retp;
	int len, clen, type;
#if MPPE_SUPPORT
	u8_t rej_for_ci_mppe = 1;	/* Are we rejecting based on a bad/missing */
	/* CI_MPPE, or due to other options?       */
#endif /* MPPE_SUPPORT */

	ret = CONFACK;
	retp = p0 = p;
	len = *lenp;

	memset(ho, 0, sizeof(ccp_options));
	ho->method = (len > 0) ? p[0] : 0;

	while(len > 0) {
		newret = CONFACK;

		if(len < 2 || p[1] < 2 || p[1] > len) {
			/* length is bad */
			clen = len;
			newret = CONFREJ;

		} else {
			type = p[0];
			clen = p[1];

			switch(type) {
#if MPPE_SUPPORT

				case CI_MPPE:
					if(!ao->mppe || clen != CILEN_MPPE) {
						newret = CONFREJ;
						break;
					}

					MPPE_CI_TO_OPTS(&p[2], ho->mppe);

					/* Nak if anything unsupported or unknown are set. */
					if(ho->mppe & MPPE_OPT_UNSUPPORTED) {
						newret = CONFNAK;
						ho->mppe &= ~MPPE_OPT_UNSUPPORTED;
					}

					if(ho->mppe & MPPE_OPT_UNKNOWN) {
						newret = CONFNAK;
						ho->mppe &= ~MPPE_OPT_UNKNOWN;
					}

					/* Check state opt */
					if(ho->mppe & MPPE_OPT_STATEFUL) {
						/*
						 * We can Nak and request stateless, but it's a
						 * lot easier to just assume the peer will request
						 * it if he can do it; stateful mode is bad over
						 * the Internet -- which is where we expect MPPE.
						 */
						if(pcb->settings.refuse_mppe_stateful) {
							ppp_error("Refusing MPPE stateful mode offered by peer");
							newret = CONFREJ;
							break;
						}
					}

					/* Find out which of {S,L} are set. */
					if((ho->mppe & MPPE_OPT_128)
					        && (ho->mppe & MPPE_OPT_40)) {
						/* Both are set, negotiate the strongest. */
						newret = CONFNAK;

						if(ao->mppe & MPPE_OPT_128)
							ho->mppe &= ~MPPE_OPT_40;
						else if(ao->mppe & MPPE_OPT_40)
							ho->mppe &= ~MPPE_OPT_128;
						else {
							newret = CONFREJ;
							break;
						}
					} else if(ho->mppe & MPPE_OPT_128) {
						if(!(ao->mppe & MPPE_OPT_128)) {
							newret = CONFREJ;
							break;
						}
					} else if(ho->mppe & MPPE_OPT_40) {
						if(!(ao->mppe & MPPE_OPT_40)) {
							newret = CONFREJ;
							break;
						}
					} else {
						/* Neither are set. */
						/* We cannot accept this.  */
						newret = CONFNAK;
						/* Give the peer our idea of what can be used,
						   so it can choose and confirm */
						ho->mppe = ao->mppe;
					}

					/* rebuild the opts */
					MPPE_OPTS_TO_CI(ho->mppe, &p[2]);

					if(newret == CONFACK) {
						int mtu;

						mppe_init(pcb, &pcb->mppe_comp, ho->mppe);
						/*
						 * We need to decrease the interface MTU by MPPE_PAD
						 * because MPPE frames **grow**.  The kernel [must]
						 * allocate MPPE_PAD extra bytes in xmit buffers.
						 */
						mtu = netif_get_mtu(pcb);

						if(mtu)
							netif_set_mtu(pcb, mtu - MPPE_PAD);
						else
							newret = CONFREJ;
					}

					/*
					 * We have accepted MPPE or are willing to negotiate
					 * MPPE parameters.  A CONFREJ is due to subsequent
					 * (non-MPPE) processing.
					 */
					rej_for_ci_mppe = 0;
					break;
#endif /* MPPE_SUPPORT */
#if DEFLATE_SUPPORT

				case CI_DEFLATE:
				case CI_DEFLATE_DRAFT:
					if(!ao->deflate || clen != CILEN_DEFLATE
					        || (!ao->deflate_correct && type == CI_DEFLATE)
					        || (!ao->deflate_draft && type == CI_DEFLATE_DRAFT)) {
						newret = CONFREJ;
						break;
					}

					ho->deflate = 1;
					ho->deflate_size = nb = DEFLATE_SIZE(p[2]);

					if(DEFLATE_METHOD(p[2]) != DEFLATE_METHOD_VAL
					        || p[3] != DEFLATE_CHK_SEQUENCE
					        || nb > ao->deflate_size || nb < DEFLATE_MIN_WORKS) {
						newret = CONFNAK;

						if(!dont_nak) {
							p[2] = DEFLATE_MAKE_OPT(ao->deflate_size);
							p[3] = DEFLATE_CHK_SEQUENCE;
							/* fall through to test this #bits below */
						} else
							break;
					}

					/*
					 * Check whether we can do Deflate with the window
					 * size they want.  If the window is too big, reduce
					 * it until the kernel can cope and nak with that.
					 * We only check this for the first option.
					 */
					if(p == p0) {
						for(;;) {
							res = ccp_test(pcb, p, CILEN_DEFLATE, 1);

							if(res > 0)
								break;		/* it's OK now */

							if(res < 0 || nb == DEFLATE_MIN_WORKS || dont_nak) {
								newret = CONFREJ;
								p[2] = DEFLATE_MAKE_OPT(ho->deflate_size);
								break;
							}

							newret = CONFNAK;
							--nb;
							p[2] = DEFLATE_MAKE_OPT(nb);
						}
					}

					break;
#endif /* DEFLATE_SUPPORT */
#if BSDCOMPRESS_SUPPORT

				case CI_BSD_COMPRESS:
					if(!ao->bsd_compress || clen != CILEN_BSD_COMPRESS) {
						newret = CONFREJ;
						break;
					}

					ho->bsd_compress = 1;
					ho->bsd_bits = nb = BSD_NBITS(p[2]);

					if(BSD_VERSION(p[2]) != BSD_CURRENT_VERSION
					        || nb > ao->bsd_bits || nb < BSD_MIN_BITS) {
						newret = CONFNAK;

						if(!dont_nak) {
							p[2] = BSD_MAKE_OPT(BSD_CURRENT_VERSION, ao->bsd_bits);
							/* fall through to test this #bits below */
						} else
							break;
					}

					/*
					 * Check whether we can do BSD-Compress with the code
					 * size they want.  If the code size is too big, reduce
					 * it until the kernel can cope and nak with that.
					 * We only check this for the first option.
					 */
					if(p == p0) {
						for(;;) {
							res = ccp_test(pcb, p, CILEN_BSD_COMPRESS, 1);

							if(res > 0)
								break;

							if(res < 0 || nb == BSD_MIN_BITS || dont_nak) {
								newret = CONFREJ;
								p[2] = BSD_MAKE_OPT(BSD_CURRENT_VERSION,
								                    ho->bsd_bits);
								break;
							}

							newret = CONFNAK;
							--nb;
							p[2] = BSD_MAKE_OPT(BSD_CURRENT_VERSION, nb);
						}
					}

					break;
#endif /* BSDCOMPRESS_SUPPORT */
#if PREDICTOR_SUPPORT

				case CI_PREDICTOR_1:
					if(!ao->predictor_1 || clen != CILEN_PREDICTOR_1) {
						newret = CONFREJ;
						break;
					}

					ho->predictor_1 = 1;

					if(p == p0
					        && ccp_test(pcb, p, CILEN_PREDICTOR_1, 1) <= 0) {
						newret = CONFREJ;
					}

					break;

				case CI_PREDICTOR_2:
					if(!ao->predictor_2 || clen != CILEN_PREDICTOR_2) {
						newret = CONFREJ;
						break;
					}

					ho->predictor_2 = 1;

					if(p == p0
					        && ccp_test(pcb, p, CILEN_PREDICTOR_2, 1) <= 0) {
						newret = CONFREJ;
					}

					break;
#endif /* PREDICTOR_SUPPORT */

				default:
					newret = CONFREJ;
			}
		}

		if(newret == CONFNAK && dont_nak)
			newret = CONFREJ;

		if(!(newret == CONFACK || (newret == CONFNAK && ret == CONFREJ))) {
			/* we're returning this option */
			if(newret == CONFREJ && ret == CONFNAK)
				retp = p0;

			ret = newret;

			if(p != retp)
				MEMCPY(retp, p, clen);

			retp += clen;
		}

		p += clen;
		len -= clen;
	}

	if(ret != CONFACK) {
		if(ret == CONFREJ && *lenp == retp - p0)
			pcb->ccp_all_rejected = 1;
		else
			*lenp = retp - p0;
	}

#if MPPE_SUPPORT

	if(ret == CONFREJ && ao->mppe && rej_for_ci_mppe) {
		ppp_error("MPPE required but peer negotiation failed");
		lcp_close(pcb, "MPPE required but peer negotiation failed");
	}

#endif /* MPPE_SUPPORT */
	return ret;
}

/*
 * Make a string name for a compression method (or 2).
 */
static const char* method_name(ccp_options* opt, ccp_options* opt2)
{
	static char result[64];
#if !DEFLATE_SUPPORT && !BSDCOMPRESS_SUPPORT
	LWIP_UNUSED_ARG(opt2);
#endif /* !DEFLATE_SUPPORT && !BSDCOMPRESS_SUPPORT */

	if(!ccp_anycompress(opt))
		return "(none)";

	switch(opt->method) {
#if MPPE_SUPPORT

		case CI_MPPE: {
			char* p = result;
			char* q = result + sizeof(result); /* 1 past result */

			ppp_slprintf(p, q - p, "MPPE ");
			p += 5;

			if(opt->mppe & MPPE_OPT_128) {
				ppp_slprintf(p, q - p, "128-bit ");
				p += 8;
			}

			if(opt->mppe & MPPE_OPT_40) {
				ppp_slprintf(p, q - p, "40-bit ");
				p += 7;
			}

			if(opt->mppe & MPPE_OPT_STATEFUL)
				ppp_slprintf(p, q - p, "stateful");
			else
				ppp_slprintf(p, q - p, "stateless");

			break;
		}

#endif /* MPPE_SUPPORT */
#if DEFLATE_SUPPORT

		case CI_DEFLATE:
		case CI_DEFLATE_DRAFT:
			if(opt2 != NULL && opt2->deflate_size != opt->deflate_size)
				ppp_slprintf(result, sizeof(result), "Deflate%s (%d/%d)",
				             (opt->method == CI_DEFLATE_DRAFT ? "(old#)" : ""),
				             opt->deflate_size, opt2->deflate_size);
			else
				ppp_slprintf(result, sizeof(result), "Deflate%s (%d)",
				             (opt->method == CI_DEFLATE_DRAFT ? "(old#)" : ""),
				             opt->deflate_size);

			break;
#endif /* DEFLATE_SUPPORT */
#if BSDCOMPRESS_SUPPORT

		case CI_BSD_COMPRESS:
			if(opt2 != NULL && opt2->bsd_bits != opt->bsd_bits)
				ppp_slprintf(result, sizeof(result), "BSD-Compress (%d/%d)",
				             opt->bsd_bits, opt2->bsd_bits);
			else
				ppp_slprintf(result, sizeof(result), "BSD-Compress (%d)",
				             opt->bsd_bits);

			break;
#endif /* BSDCOMPRESS_SUPPORT */
#if PREDICTOR_SUPPORT

		case CI_PREDICTOR_1:
			return "Predictor 1";

		case CI_PREDICTOR_2:
			return "Predictor 2";
#endif /* PREDICTOR_SUPPORT */

		default:
			ppp_slprintf(result, sizeof(result), "Method %d", opt->method);
	}

	return result;
}

/*
 * CCP has come up - inform the kernel driver and log a message.
 */
static void ccp_up(fsm* f)
{
	ppp_pcb* pcb = f->pcb;
	ccp_options* go = &pcb->ccp_gotoptions;
	ccp_options* ho = &pcb->ccp_hisoptions;
	char method1[64];

	ccp_set(pcb, 1, 1, go->method, ho->method);

	if(ccp_anycompress(go)) {
		if(ccp_anycompress(ho)) {
			if(go->method == ho->method) {
				ppp_notice("%s compression enabled", method_name(go, ho));
			} else {
				ppp_strlcpy(method1, method_name(go, NULL), sizeof(method1));
				ppp_notice("%s / %s compression enabled",
				           method1, method_name(ho, NULL));
			}
		} else
			ppp_notice("%s receive compression enabled", method_name(go, NULL));
	} else if(ccp_anycompress(ho))
		ppp_notice("%s transmit compression enabled", method_name(ho, NULL));

#if MPPE_SUPPORT

	if(go->mppe) {
		continue_networks(pcb);		/* Bring up IP et al */
	}

#endif /* MPPE_SUPPORT */
}

/*
 * CCP has gone down - inform the kernel driver.
 */
static void ccp_down(fsm* f)
{
	ppp_pcb* pcb = f->pcb;
#if MPPE_SUPPORT
	ccp_options* go = &pcb->ccp_gotoptions;
#endif /* MPPE_SUPPORT */

	if(pcb->ccp_localstate & RACK_PENDING)
		UNTIMEOUT(ccp_rack_timeout, f);

	pcb->ccp_localstate = 0;
	ccp_set(pcb, 1, 0, 0, 0);
#if MPPE_SUPPORT

	if(go->mppe) {
		go->mppe = 0;

		if(pcb->lcp_fsm.state == PPP_FSM_OPENED) {
			/* If LCP is not already going down, make sure it does. */
			ppp_error("MPPE disabled");
			lcp_close(pcb, "MPPE disabled");
		}
	}

#endif /* MPPE_SUPPORT */
}

#if PRINTPKT_SUPPORT
/*
 * Print the contents of a CCP packet.
 */
static const char* const ccp_codenames[] = {
	"ConfReq", "ConfAck", "ConfNak", "ConfRej",
	"TermReq", "TermAck", "CodeRej",
	NULL, NULL, NULL, NULL, NULL, NULL,
	"ResetReq", "ResetAck",
};

static int ccp_printpkt(const u_char* p, int plen, void (*printer)(void*, const char*, ...), void* arg)
{
	const u_char* p0, *optend;
	int code, id, len;
	int optlen;

	p0 = p;

	if(plen < HEADERLEN)
		return 0;

	code = p[0];
	id = p[1];
	len = (p[2] << 8) + p[3];

	if(len < HEADERLEN || len > plen)
		return 0;

	if(code >= 1 && code <= (int)LWIP_ARRAYSIZE(ccp_codenames) && ccp_codenames[code - 1] != NULL)
		printer(arg, " %s", ccp_codenames[code - 1]);
	else
		printer(arg, " code=0x%x", code);

	printer(arg, " id=0x%x", id);
	len -= HEADERLEN;
	p += HEADERLEN;

	switch(code) {
		case CONFREQ:
		case CONFACK:
		case CONFNAK:
		case CONFREJ:

			/* print list of possible compression methods */
			while(len >= 2) {
				code = p[0];
				optlen = p[1];

				if(optlen < 2 || optlen > len)
					break;

				printer(arg, " <");
				len -= optlen;
				optend = p + optlen;

				switch(code) {
#if MPPE_SUPPORT

					case CI_MPPE:
						if(optlen >= CILEN_MPPE) {
							u_char mppe_opts;

							MPPE_CI_TO_OPTS(&p[2], mppe_opts);
							printer(arg, "mppe %s %s %s %s %s %s%s",
							        (p[2] & MPPE_H_BIT) ? "+H" : "-H",
							        (p[5] & MPPE_M_BIT) ? "+M" : "-M",
							        (p[5] & MPPE_S_BIT) ? "+S" : "-S",
							        (p[5] & MPPE_L_BIT) ? "+L" : "-L",
							        (p[5] & MPPE_D_BIT) ? "+D" : "-D",
							        (p[5] & MPPE_C_BIT) ? "+C" : "-C",
							        (mppe_opts & MPPE_OPT_UNKNOWN) ? " +U" : "");

							if(mppe_opts & MPPE_OPT_UNKNOWN)
								printer(arg, " (%.2x %.2x %.2x %.2x)",
								        p[2], p[3], p[4], p[5]);

							p += CILEN_MPPE;
						}

						break;
#endif /* MPPE_SUPPORT */
#if DEFLATE_SUPPORT

					case CI_DEFLATE:
					case CI_DEFLATE_DRAFT:
						if(optlen >= CILEN_DEFLATE) {
							printer(arg, "deflate%s %d",
							        (code == CI_DEFLATE_DRAFT ? "(old#)" : ""),
							        DEFLATE_SIZE(p[2]));

							if(DEFLATE_METHOD(p[2]) != DEFLATE_METHOD_VAL)
								printer(arg, " method %d", DEFLATE_METHOD(p[2]));

							if(p[3] != DEFLATE_CHK_SEQUENCE)
								printer(arg, " check %d", p[3]);

							p += CILEN_DEFLATE;
						}

						break;
#endif /* DEFLATE_SUPPORT */
#if BSDCOMPRESS_SUPPORT

					case CI_BSD_COMPRESS:
						if(optlen >= CILEN_BSD_COMPRESS) {
							printer(arg, "bsd v%d %d", BSD_VERSION(p[2]),
							        BSD_NBITS(p[2]));
							p += CILEN_BSD_COMPRESS;
						}

						break;
#endif /* BSDCOMPRESS_SUPPORT */
#if PREDICTOR_SUPPORT

					case CI_PREDICTOR_1:
						if(optlen >= CILEN_PREDICTOR_1) {
							printer(arg, "predictor 1");
							p += CILEN_PREDICTOR_1;
						}

						break;

					case CI_PREDICTOR_2:
						if(optlen >= CILEN_PREDICTOR_2) {
							printer(arg, "predictor 2");
							p += CILEN_PREDICTOR_2;
						}

						break;
#endif /* PREDICTOR_SUPPORT */

					default:
						break;
				}

				while(p < optend)
					printer(arg, " %.2x", *p++);

				printer(arg, ">");
			}

			break;

		case TERMACK:
		case TERMREQ:
			if(len > 0 && *p >= ' ' && *p < 0x7f) {
				ppp_print_string(p, len, printer, arg);
				p += len;
				len = 0;
			}

			break;

		default:
			break;
	}

	/* dump out the rest of the packet in hex */
	while(--len >= 0)
		printer(arg, " %.2x", *p++);

	return p - p0;
}
#endif /* PRINTPKT_SUPPORT */

#if PPP_DATAINPUT
/*
 * We have received a packet that the decompressor failed to
 * decompress.  Here we would expect to issue a reset-request, but
 * Motorola has a patent on resetting the compressor as a result of
 * detecting an error in the decompressed data after decompression.
 * (See US patent 5,130,993; international patent publication number
 * WO 91/10289; Australian patent 73296/91.)
 *
 * So we ask the kernel whether the error was detected after
 * decompression; if it was, we take CCP down, thus disabling
 * compression :-(, otherwise we issue the reset-request.
 */
static void ccp_datainput(ppp_pcb* pcb, u_char* pkt, int len)
{
	fsm* f;
#if MPPE_SUPPORT
	ccp_options* go = &pcb->ccp_gotoptions;
#endif /* MPPE_SUPPORT */
	LWIP_UNUSED_ARG(pkt);
	LWIP_UNUSED_ARG(len);

	f = &pcb->ccp_fsm;

	if(f->state == PPP_FSM_OPENED) {
		if(ccp_fatal_error(pcb)) {
			/*
			 * Disable compression by taking CCP down.
			 */
			ppp_error("Lost compression sync: disabling compression");
			ccp_close(pcb, "Lost compression sync");
#if MPPE_SUPPORT

			/*
			 * If we were doing MPPE, we must also take the link down.
			 */
			if(go->mppe) {
				ppp_error("Too many MPPE errors, closing LCP");
				lcp_close(pcb, "Too many MPPE errors");
			}

#endif /* MPPE_SUPPORT */
		} else {
			/*
			 * Send a reset-request to reset the peer's compressor.
			 * We don't do that if we are still waiting for an
			 * acknowledgement to a previous reset-request.
			 */
			if(!(pcb->ccp_localstate & RACK_PENDING)) {
				fsm_sdata(f, CCP_RESETREQ, f->reqid = ++f->id, NULL, 0);
				TIMEOUT(ccp_rack_timeout, f, RACKTIMEOUT);
				pcb->ccp_localstate |= RACK_PENDING;
			} else
				pcb->ccp_localstate |= RREQ_REPEAT;
		}
	}
}
#endif /* PPP_DATAINPUT */

/*
 * We have received a packet that the decompressor failed to
 * decompress. Issue a reset-request.
 */
void ccp_resetrequest(ppp_pcb* pcb)
{
	fsm* f = &pcb->ccp_fsm;

	if(f->state != PPP_FSM_OPENED)
		return;

	/*
	 * Send a reset-request to reset the peer's compressor.
	 * We don't do that if we are still waiting for an
	 * acknowledgement to a previous reset-request.
	 */
	if(!(pcb->ccp_localstate & RACK_PENDING)) {
		fsm_sdata(f, CCP_RESETREQ, f->reqid = ++f->id, NULL, 0);
		TIMEOUT(ccp_rack_timeout, f, RACKTIMEOUT);
		pcb->ccp_localstate |= RACK_PENDING;
	} else
		pcb->ccp_localstate |= RREQ_REPEAT;
}

/*
 * Timeout waiting for reset-ack.
 */
static void ccp_rack_timeout(void* arg)
{
	fsm* f = (fsm*)arg;
	ppp_pcb* pcb = f->pcb;

	if(f->state == PPP_FSM_OPENED && (pcb->ccp_localstate & RREQ_REPEAT)) {
		fsm_sdata(f, CCP_RESETREQ, f->reqid, NULL, 0);
		TIMEOUT(ccp_rack_timeout, f, RACKTIMEOUT);
		pcb->ccp_localstate &= ~RREQ_REPEAT;
	} else
		pcb->ccp_localstate &= ~RACK_PENDING;
}

#endif /* PPP_SUPPORT && CCP_SUPPORT */
